Composition and method for bleaching milling products



Patented Feb. 10, 1942' COMPOSITION AND LIETHOD FOR BLEACH- ING MILLINGPRODUCTS Frederic 11. Penn, Dallas, Tex.

No Drawing. Application June 11; 1941, Serial No. 397,622

15 Claims.

My invention relates to the treatment of'wheat flour and other millingproducts, and more particularly has reference to the bleaching of flourand the like by means of non-flammable or ganic peroxide compositions,which increase the ash content of the flour only a negligible amount.

Organic peroxides, notably benzoyl peroxide, derived from hydrogenperoxide, have long been used as bleaching agents for flour. They arequite flammable, and decompose in the presence of spark, flame, ortemperatures above 105 0., and'are even explosive under certainconditions. Therefore, considerable caution has been necessary in thehandling of these organic peroxides.

To prepare organic peroxides for bleaching flour, it is necessary thatthe organic peroxide be in dry finely divided form in order to beintimately mixed with the flour. To accomplish fine grinding, theorganic peroxide is ordinarily mixed with an inert material, such asdicalcium phosphate or the like, and then ground to the desiredfineness. Although these inert materials prevent the decomposition ofthe organic peroxides during the grinding process, they have no efiecton the flammability of the organic peroxide.

When water soluble alkali metal phosphates, borates and sulphatescontaining, per mole, about two to about ten moles of water ofcrystallization are used as a carrier and for grinding the organicperoxides, the flammability of the organic peroxides, when used in thamount of about twenty per cent., can be prevented. The organic peroxidebleaching compositions containing alkali metal salts, having per'moleabout two to about ten moles of water of crystallization, are subject topacking and lumping, and as such are not satisfactory for use, and forthis reason, it is necessary to include a packing and lumping inhibitorwith the organic peroxide, alkali metal salt compositions.

This application is a continuation in part of my co-pendingapplications, No. 387,781 and No. 387,782.

An object of this invention is to provide nonfiammable organic peroxidecompositions in dry powdered non-packing and non-lumping form.

wheat, etc. The patent flour is the best grade, having an ash content ofnot more than .400%. Flour having an ash content of more than .400% isclassified as clear and is sold at lower prices than patent flour.

Potassium or sodium phosphate, when used as a carrier and containingwater of crystallization,

'in combination with organic peroxides, do not increase the ash contentof the flour to the extent as does calcium sulfate or calcium phosphateor other calcium compounds. Water sol-- uble alkali metal salts arecapable of carrying more moles of water of crystallization than thewater insoluble alkaline earth metal salts. For instance, the increaseof the ash in the flour due to the added benzoyl peroxide bleachingagent is almost twice as much when calcium sulfate, which contains amaximum of only two moles of water of crystallization, than when sodiumphosphate containing ten moles of 'water of crystallization is used as acarrier.

Liquid peroxides, as acetyl peroxides, or inactive peroxides, asphthalyl peroxide, are not suitable for the purpose of this invention.The peroxides intended for use in the present invention are theso-called active organic peroxides, these being primarily the peroxidesof the kind that release nascent oxygen. The active organic peroxides ofthe type mentioned are the ones which are particularly objectionablebecause of flammability.

In my prior patent, No. 2,208,471, July 16, 1940, I have shown that theflammability of the active organic peroxides can be prevented by meansof certain aluminum sulfates containing about twenty-four moles oi.water of crystallization. I have now found that this result can also beaccomplished by combining with the active organic peroxides watersoluble alkali metal salts containing, per mole, about two to about tenmoles of water of crystallization.

Accordingly, the dry powdered bleaching composition of the presentinvention comprises, in addition to the active organic peroxide, asufflcient quantity of an alkali metal salt of the character abovementioned to prevent the flammability of the peroxide. Among these saltsare sodium or potassium phosphate, sodium sulfate, potassium and sodiumborate, containing from about two to about ten moles of water ofcrystallization, the latter characteristic being the one which rendersthe compounds efl'ective in preventing flammability of the activeorganic peroxides. In this respect, the salts used in the presentinvention differ in form from the calcium sulfate, calcium phosphate andmagnesium carbonates heretofore employed with organic peroxides. Thepreferred water soluble alkali metal salt of this invention forpreventing flammability is sodium pyi'o phosphate containing about tenmoles of water of crystallization.

The alkali metal salts of the present invention, due to their watercontent, are more or less damp, and hence not susceptible'to finegrinding, and for this reason, a packing inhibitor, such as anhydrousmagnesium carbonate, in finely divided form, should preferably be usedto facilitate fine grinding and to prevent packing of the bleachingcomposition. In place of anhydrous magnesium carbonate, other packinganhydrous inhibitors, such as anhydrous tricalcium phosphate, aluminumoxide or aluminum silicate, may be used.

Benzoyl peroxide is' the preferred peroxide used as the active organicperoxide, but other active peroxides, as cinnamoyl and phenyl acetylperoxide may also be used as the bleaching com ponent of thecomposition.

Illustrative'of the preparation of the preferred non-flammable organicperoxide composition,

twenty grams of dry benzoyl peroxide, 65 grams of sodium pyrophosphatecontaining about ten moles of water of crystallization, and 15 grams ofanhydrous magnesium carbonate, are mixed together and ground to a finelydivided powder. The resultant product is non-flammable, nonexplosive,and is ready for use as a flour bleaching agent.

In place of sodium pyrophosphate of the example given above, sodiumborate or sodium sulfate containing about two to about ten moles ofwater of crystallization may be used.

peroxide, and an anhydrous packing inhibitor.

3. A flour bleaching composition comprising a dry free flowing powderedmixture of an active organic peroxide having substantial flour bleachingproperties, a water soluble alkali metal phosphate containing, per mole,about two to about ten moles of water of crystallization, in sumcientamount to prevent flammability of the organic peroxide, and anhydrousmagnesium carbonate.

4. A flour bleaching composition comprising a dry free flowing powderedmixture of benzoyl peroxide, a water soluble alkali metal phosphatecontaining, per mole, about two to about ten moles of water ofcrystallization, in sui'flcient amount to prevent flammability of thebenzoyl peroxide, and an anhydrous packing inhibitor.

5. A flour bleaching composition comprising a dry free flowing powderedmixture of benzoyl In practicing the flour bleaching method ofthisinvention, the non-flammable benzoyl peroxide, water-containing sodiumpyrophosphate, anhydrous magnesium carbonate composition, produced asabove described, is fed directly into the flour stream at any convenientpoint during the milling operation, and intimately mixed with the flourby means of powder feeding machines now in general use in the mills, inthe proportion of about A; ounce to one barrel (196 pounds) of flour.For a thorough distribution of such small amounts of the bleachingcomposition in the flour, the composition should be in the form of a dryfree flowing finely divided powder. A satisfactory bleaching is obtainedby exposing the flour to the action of the bleaching composition forabout twenty-four hours.

In the appended claims, I have characterized the peroxides as active andhaving substantial flour bleaching properties, in order to distinguishthem from those organic peroxides which are of insufficient activity andbleaching power to effect bleaching of the flour.

Having described my invention, I claim:

1. A flour bleaching composition comprising a dry free flowing powderedmixture of an active organic peroxide having substantial flour bleachingproperties, a water soluble alkali metal salt containing, per mole,about two to about ten moles of water of crystallization, in sufficientamount to prevent flammability of the organic peroxide, and an anhydrouspacking inhibitor.

2. A flour bleaching composition comprising a dry free flowing powderedmixture of an active organic peroxide having substantial flour bleaching properties, a water soluble alkali metal phosphate containing, permole, about two to about ten moles of water of crystallization, insufficient amount to prevent flammability of the organic peroxide, awater soluble alkali metal borate, containing, per mole, about flve toabout ten moles of water of crystallization, in suflicient amount toprevent flammability of the benzoyl peroxide, and anhydrous magnesiumcarbonate.

6. A flour bleaching composition comprising a dry'iree flowing powderedmixture of benzoyl peroxide, sodium borate containing, per mole, aboutten moles of water of crystallization, in suflicient amount to preventflammability of the benzoyl peroxide, and anhydrous magnesium carbonate.

7. A flour bleaching composition comprising a dry free flowing powderedmixture of benzoyl peroxide, sodium pyrophosphate containing, per mole,about ten moles of water of crystallization, in sufficient amount toprevent flammability oi' the benzoyl peroxide, and anhydrous magnesiumcarbonate.

8. A flour bleaching composition comprising a dry free flowing powderedmixture of benzoyl peroxide, sodium sulfate containing, per mole, aboutten moles of water of crystallization, in sufiicient amount to preventthe flammability of the benzoyl peroxide, and an anhydrous magnesiumcarbonate.

9. A method for bleaching wheat flour and other milling products, whichcomprises mixing with the dry milling product a dry free flowingpowdered mixture of an active organic peroxide having substantialbleaching properties, an anhydrous packing inhibitor, and a watersoluble alkali metal salt containing, per mole, about two to about tenmoles of water of crystallation, the peroxide being in sumcient amountto bleach the milling product and said water soluble alkali metal saltbeing in suiflcient amount toprevent the flammability of the peroxide,and subjecting the dry milling product to the action of said mixture fora sufficient time to bleach the produc 10. A method for bleaching wheatflour and other milling products which comprises mixing with the drymilling product a dry free flowing powdered mixture of an active organicperoxide having substantial bleaching properties, an anhydrous packinginhibitor, and alwater soluble alkali metal phosphate, containing, permole, about two to about ten moles of water of crystallization, theperoxide bein in suflicient amount to bleach the milling product andsaid phosphate being in sumcient amo t to prevent flammability of theperoxid and subjecting the dry milling product to the action of saidmixture for a suflicient time to bleach the product.

11. A method for bleaching what flour and other milling prciucts whichcomprises mixing bleach the milling product and said borate being withthe dry milling product a dry free flowing powdered mixture of benzoylperoxide, anhydrous magnesium carbonate, and a water soluble alkalimetal salt containing, per mole, about two to about ten moles of waterof crystallization, the peroxide being'in sufficient amount to bleachthe milling product and said salt being in suflicient amount to preventflammability of the peroxide, and subjecting the dry milling produce tothe action of said mixture for a sufficient time to bleach the product.

12. A method for bleaching wheat flour and other milling products whichcomprises mixing with the dry milling product a dry free flowingpowdered mixture of benzoyl peroxide, an anhydrous packing inhibitor,and a water soluble alkali metal borate containing, per mole, about flveto about ten moles of water of crystallization, the peroxide being insufllcient amount to in suflicient amount to prevent flammability of theperoxide, and subjecting the dry milling product to the action of saidmixture for a sufilcient time to bleach the product.

13. A method for bleaching wheat flour and other milling products whichcomprises mixing with the dry milling product a dry free flowingpowdered mixture of benzoyl peroxide, anhydrous magnesium carbonate andsodium borate containing per mole, about ten moles of water ofcrystallization, the benzoyl peroxide being in I suflicient amount tobleach the milling product and said borate being in suflicient amount toprevent flammability of the-peroxide, and subjecting the dry millingproductto the action of said mixture for a sufllcient time to bleach themilling product.

14. A method for bleaching wheat flour and other milling products whichcomprises mixing with the milling product a dry free flowing powderedmixture of benzoyl peroxide, anhydrous magnesium carbonate and sodiumpyrophosphate containing, per mole, about tenmoles of water ofcrystallization, the benzoyl peroxide being in sufficient amount tobleach the milling product, and the sodium pyropl'b'sphate being insuflicient amount to prevent flammability of the benzoyl peroxide, andsubjecting the dry milling product to the action of said mixture for asufilcient time to bleach the milling product.

15. A method for bleaching wheat flour and other milling products whichcomprises mixing with the milling product a dry free flowing powderedmixture of benzoyl peroxide, anhydrous magnesium carbonate and sodiumsulfate, containing per mole about ten moles of water ofcrystallization, the benzoyl peroxide being in suflicient amount tobleach the milling product and the sodium sulfate being in suflicientamount to prevent flammability of the benzoyl peroxide, and subjectingthe dry milling product to the action of; said mixture for a sufficienttime to .bleach the milling product.

FREDERIC H. PENN.

